Improved GridColumns validation
Improved GridColumns validation

vascotenner/holoviews,ioam/holoviews,ioam/holoviews,ioam/holoviews,vascotenner/holoviews,basnijholt/holoviews,basnijholt/holoviews,basnijholt/holoviews,vascotenner/holoviews